1. Field of the Invention
The present invention generally relates to a power supply for use in a portable electronic apparatus, such as a camera, to which small size dry batteries are employed, and more particularly to a power supply which has a battery housing for accommodating dry batteries therein, a battery door for exposing and closing an opening of the housing and a detector for detecting, when the door is closed, such a condition as to whether or not the batteries are accommodated in the housing.
2. Description of the Related Art
The portable electronic apparatus such as a camera generally has a power supply. For instance, a known power supply for a portable camera has a battery housing for accommodating a plurality of small size cylindrically dry batteries, for example four batteries, therein, and a hinged battery door which is so connected to an edge of the opening of the housing as to expose and close the opening. For example, in a camera, the batteries are generally arranged in the housing parallel to each other and in two lines. Namely, a pair of inner adjacent batteries are arranged at positions close to the hinge of the door, while the other pair of outer batteries are arranged at the different positions remote from the hinge. Such arrangement of the batteries is similar to an arrangement shown in FIG. 3 which illustrates an embodiment of the present invention.
It is to be noted here that a specific type of camera has a voltage metering device for the batteries accommodated in the battery housing. According to the device, it can be detected whether or not new batteries generate the predetermined voltage. Furthermore, some cameras are provided with a microcomputer for controlling various operations, such as film frame counting, and a back-up battery for temporarily holding the predetermined data stored in the microcomputer, such as the number of film frames which has been taken, while the main batteries, i.e. the batteries in the power supply, are removed from the battery housing for the purpose of replacement. In these cases, the camera should be provided with a detector for detecting such a condition that a new set of batteries is inserted in the battery housing. When a new set of batteries is inserted in the battery housing, the detector will generate a start signal for starting the operation of the voltage metering device and reading out the data from a memory circuit such as a RAM to a CPU in the microcomputer.
Meanwhile, in the case where a plurality of cylindrically-shaped batteries, for example four cylindrical batteries, are accommodated in the battery housing, it is quite important that the detector be operated after or at the time when all of the batteries to be inserted are completely connected to each other in series. If the detector is operated when, for instance, only one or two batteries are inserted in the battery housing, the voltage metering device may indicate an incorrect voltage value, and some troubles will be caused in reading out the data.